If they actually do what they say the do, then yes. Thier is no evidence that they are lying, so for now its probebly save to assume that they can not read your messages.
Thats what I said. You have to trust them. As far as we know they can not read it. Its fully possible that its not true but its far more likely that it is true.
If the work together with the NSA then its more likly that they deploy bad updates to individuels rather then deploying a backdoor to everybody. That is to easy to detect and it would be a marketing desaster.
No, you said it is safe to assume they can't read your messages, which is the exact opposite to what Snowden said. What you personally think is true, likely etc is irrelevant. Facebook could be compelled to release private keys/data to the US government and not tell anyone and you'd be none the wiser.
